1. Field of the Invention
This invention relates to an inhaler for delivering medicine to a patient.
2. Description of Related Art
A widespread way to administer medicine to a patient is by using a device that atomizes the drug, which the patient then inhales via a mouthpiece, mask, or hood. Such "inhalers" or "nebulizers" are disclosed in the following texts:
U.S. Pat. No. 3,658,059 (Steil), Apr. 25, 1972;
U.S. Pat. No. 4,007,238 (Glenn), Feb. 8, 1977;
U.S. Pat. No. 4,116,387 (Kremer) Sep. 26, 1978;
U.S. Pat. No. 4,674,491 (Brugger) Jun. 23, 1987; and
U.S. Pat. No. 4,746,067 (Svoboda), May 24, 1988.
In order for an inhaler to be usable and effective for a wide variety of applications, patients, and locations, an inhaler should ideally have the following characteristics:
1. The degree of atomization should be high. In other words, as much of a dose as possible should consist of particles as small as possible.
2. The medicine that is stored in the device should never come in contact with the surrounding air or this contact should at least be kept to a minimum. Such a feature would insure that the medicine would not evaporate or become contaminated or diluted and it would also guarantee that medicine, which is often very expensive or in very limited supply (such as certain known drugs used to treat AIDS patients), is not wasted. Moreover, proper containment also avoids exposing others to the medicine. The medicine should be effectively shielded against contamination up until the moment at which it is atomized.
3. It should be possible to administer medicine in both liquid and powder form.
4. The device should protect the patient from an overdose. In many conventional systems, medicine is atomized when the patient or operator presses some form of "trigger", which then causes compress air to be channeled to an atomization chamber or region within the device. In many known inhalers of this type, medicine is administered to the patient as long as the trigger is depressed. This means that the patient or operator must know when to release the trigger in order to stop the flow of air and end the "dose".
5. Atomized medicine that remains in or has just left the mouthpiece, mask, or hood, or which is still trapped in some cavity of the device, should not be wasted. Such a feature would be of particular importance for patients with breathing difficulties such as those with severe asthma, or unconscious patients.
6. It should be possible to use the inhaler with little or no modification for different types of medicine in order to reduce the cost of using such inhalers, and also for it to have the widest possible area of use.
7. The patient should not need different systems when she is stationary (for example, in a hospital bed) and when she is moving around. The ability to mount an inhaler in a stationary configuration benefits not only individual patients who must remain in the home or hospital, such as AIDS patients, but it is also particularly useful for implementing mass vaccination schemes. A portable inhaler that is also designed to allow easy adaptation to efficient stationary mounting and operation could then be transported to remote or underdeveloped areas.
8. The inhaler should provide effective treatment but should not be cumbersome, and it should be as quite as possible in operation so as not to inconvenience or embarrass the user or disturb others.
9. An inhaler should function simply and it should be easy to take apart and put together. This increases reliability and also promotes and facilitates and easy cleaning.
10. In order to ensure maximum hygiene, it should be possible to clean or sterilize the inhaler in, for example, an autoclave.
Existing inhalers or "nebulizers", such as those described in the patents listed above, fail to meet one or more of the preceding design goals. It is accordingly an object of this invention to provide an inhaler that meets these goals.